Re: looking for old Datamation poster on Normalizing

David Cressey wrote:
PMFJI. I've allways been disturbed by the presentation of 4NF in the
"puppies & tricks" poster. It seems to me that there's a misprint,
somewhere, or that the key of one of the tables has undergone a shift
between the 3NF example and the 4NF example. Am I the only one who sees a
problem, or has this been discussed before?

The keys (assuming /italics/ indicate keys) are wrong. It would make
more sense if the key for the initial allegedly non-4NF "Puppy Tricks"
were { Puppy Number, Trick ID, Costume }, and the the key for "Puppy
Costumes" were { Puppy Number, Costume }, but the explanation is still
bad. As presented, it looks more like an example of 2NF than 4NF.
--
Jon
.